any of the rows of seats occupied by the backbenchers.
Compare front bench.
Origin of back bench
First recorded in 1870–75
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for back bench
Why is a general so lionized hanging up his uniform for a back-bench position?
But the Virginia congressman has the most to gain from a back-bench revolt.